Electric plug is a necessity in our daily life. Blades of the electric plug of the prior art are secured by the clamping force provided by conductors in the socket. At initial, the blades may be well held in position; however, later, they tend to get loosening up and falling off accidentally. Such interruption of power supply may cause disturbance to the user particularly when he is operating certain electric appliance or information system. In addition, it may also affect the stability of such appliance or system. In case of a three-in-one conversion plug with only one pair of blades, a sudden power interruption is not uncommon when such blades fail to be secured in the socket due to the fatigue of the blades or when any plug is pulled off from the conversion plug, the power supply to the other two plugs are interrupted at the same time.
In some types of three-in-one conversion plug(9) as illustrated in FIG. 20, its blades(92) are made rotatable for certain degrees, wherein, a rotator(91) allowing proper rotation and stop at a position as desired is accommodated in a recess provided at the edge of the conversion plug(91), said blades(92) and conducting tongues(93) are each directly bound with a rivet(94) and said blades(92) are respectively connected to said conducting tongues; since the blades(92) are linked to the rotator(91), by turning the blades(92), the rotator(91) rotates accordingly and the conversion plug can be plugged into the outlet depending on the angle as desired by the user. However, the direct binding of the blades(92) and the conducting tongues(93) each with a rivet(94) usually would wind up in that the contact between the blade(92) and the conducting tongue(93) either gets too tight or too loose. As a result, when the rotator(9) is moved by turning the blades(92), it becomes difficult to turn the blades(92) or blades fall loosen easily even with a slight touch making the turning very awkward.
Therefore, a modified version of the conversion plug(9) is further provided with a packing(95) at where corresponding to the joint of the blade(92) and the conducting tongue(93) as illustrated in FIG. 12. In addition, a rivet is used to penetrate through the conducting tongue(93), the packing(95) and the blade(92) for connection. The modified conversion plug though prevents the insertion of the blades(92) from getting too tight or too loose by reducing the friction generated from the rotation of the corresponding conducting tongue(93) of the blade(92) with the packing(95), the process to connect the conducting tongue(93), the packing(95), which is a very small part, and the rivet(94) is very complicate and extra attention is required, thus the modified version prevents effective cost reduction due to increased man-hour.